Brake Master Cylinder problems of the 2006 Cadillac DTS

I started the car, applied the brake, put it in drive and began to pull out of parking space. I applied the brakes and the pedal hit the carpet. I bumped the car in front of me. No damage. I towed the car to a garage and they found that the brake lines, 2 of them had rusted thru and there was damage to a third. The front calipers are also so rusted out that they cannot be adjusted to bleed the lines and the master cylinder is leaking. The entire system is rust effected. The car is a massachusetts car I just transported to calif. Gm should be responsible for these faulty vehicles and brake problems. To completely replace the brake lines will cost thousands. This is a major safety issue. If it had happened at highway speeds, it would have been very serious.